Multi-speed-transmissions, for example transmissions for utility vehicles, are usually designed as multi-group transmission with eight, nine, ten, twelve or more speeds. This is achieved by combining at least two individual multi-speed transmissions. The complete transmission is frequently composed of a main transmission and a range group transmission, where in most cases the range group transmission is downstream from the main transmission and, for example, enables two gear ratio ranges, whereby the number of speeds of the main transmission is doubled.
Furthermore, multi-group transmissions are known that are divided into an upstream group, a main transmission and a range group. The upstream group is most frequently designed as a splitter group to compress the speeds and comprises two speeds and the main transmission and the upstream group are designed to have a 1- or 2-countershaft construction.
In multi-group transmissions of the prior art, the range group transmission is designed as a planetary gear set of short dimensions or is realized as a two-countershaft-group, where the reverse gear is integrated into the main transmission. An example of a reverse gear integrated in a wheel-reversing transmission or main transmission of a multi-group transmission can be found in DE 30 12 778 filed by the applicant of this current invention. The integration of the reverse gear into the main transmission demands appropriate gears as well as an additional shifting element for shifting the reverse gear.
A planetary range group transmission of a multi-group transmission is already known to the applicant from DE 41 21 709, for example. It comprises a sun gear arranged rotationally fixed on an output shaft of the main transmission, a ring gear connected rotationally fixed to the transmission housing, via a first clutch, for shifting a slow gear, and a bar forming the output drive. A second clutch is provided that can be activated jointly with the first clutch and connects the shaft to the output shaft of the main transmission when the first clutch is disengaged.
The object of the present invention is to provide a motor vehicle multi-group transmission that requires less space than a corresponding transmission of the prior art. Furthermore, the inventive transmission should be lightweight and economical to manufacture. Finally, the inventive multi-speed transmission should demonstrate optimal efficiency at all speeds.